Sonny Bill Williams has arrived in Japan to begin the next chapter of his headline-grabbing career.

Williams will train with Top League side the Wild Knights for the first time on Thursday at the start of a lucrative 10-game contract that is expected to precede a return to National Rugby League in Australia with the Sydney Roosters next year.

The 27-year-old bid farewell to New Zealand rugby following the All Blacks' 22-0 victory over Australia last weekend, thanks to an agreement to delay his move to Japan, and is relishing a fresh challenge.

"I just want to experience the culture, and get to understand it and embrace it," Williams told ONE Sport. "It will take me a while to break the language barrier, but hopefully in the next month or two, I can do that."

Williams, A World Cup winner who also won the Super Rugby title with the Chiefs earlier this year, has not ruled out a return to rugby union at a later date and the New Zealand Rugby Union are also open to the possibility

"Who knows? Hopefully down the track I can come back and play in New Zealand," he said following his last appearance - for now - for the All Blacks. "Winning with the Chiefs and tonight has made it a little bit more happy leaving in that sense. But still, when you form close friendships, it is tough to leave."